Summary:
The Apollo Hill deposit comprises a series of gold-bearing sheeted and stockwork-like vein sets hosted along a NW-trending, relatively steep easterly-dipping shear zone in typical Archean greenstone rock types.
The mineralised zone extends over a strike length of approximately 2.7 kilometres and has been intersected by drilling to approximately 570 metres vertical depth. The depth of complete oxidation averages around 4 metres, with depth to fresh rock averaging around 20 metres.
The Apollo Hill project comprises two deposits/trends: the main Apollo Hill deposit comprised of the ‘Main lode’ and ‘Hanging Wall’ Lodes in the northwest of the project area, and the Southern Apollo Hill Corridor trend, comprised of the Wadget-Ra-Iris-Tefnut lodes in the south. Gold mineralisation is associated with quartz veins and carbonate-pyrite alteration along a steeply north-east dipping contact between a schist unit to the west, and mafic dominated volcanic and intrusive rocks to the east. The combined mineralised zones extend over a strike length of approximately 3km and have been intersected by drilling to approximately 500m vertical depth.
Deposit Geology
The Apollo Hill Deposit represents a substantial gold resource within a greenstone belt characterised by a diverse geological and structural framework. The host rocks primarily consist of fine to medium-grained basalts, medium to coarse-grained dolerites, mafic schists, and interflow sediments. Central to the deposit’s geology is the renowned Apollo Hill Shear Zone, a NW-trending, approximately 1 km wide structural feature that can be traced on geophysics for over 24 km. This shear zone is interpreted as a fault splay associated with the KeithKilkenny tectonic zone, dipping between 45° and 60° northeast, and is a key control on mineralisation, structural deformation, and fluid pathways within the system.
The greenstone sequence hosting the gold mineralisation can be subdivided into three primary lithological and structural settings: the Main Lode, the Footwall Lodes, and the Hanging Wall Lodes . The Main Lode contains the bulk of the known gold resources and is mainly composed of fine- to coarse-grained dolerite and basalt. Within this zone, intermittent schist units occur, often aligned along NW-SE, E-W, and N-S structural trends that cut through the Apollo Hill Shear Zone. These zones have undergone brittle-ductile deformation, resulting in significant strain, and host the majority of vein-hosted gold mineralisation. Mineralisation is predominantly vein-related, with mineralising fluids exploiting structural features and depositing gold in or near fractures and brittle openings. These mineralising fluids are associated with alteration halos comprising silica and pyrite, and they often occur in zones of brittle deformation. Notably, gold appears disseminated throughout the Main Lode without clear lithological discrimination, indicating a pervasive mineralising process influenced heavily by structural controls.
The Footwall Zones, located on the western flank of the shear zone, is an area of notable geomorphological and geological interest. It exhibits a sharp topographical decline, forming a plateau created by more ductile units that weather differently compared to the brittle mafic rocks in the Hanging Wall. The footwall itself is interpreted as an amalgamation of various lithologies, heavily altered by intense deformation and secondary fluid activity. These rocks have undergone significant replacement mineralisation, mainly featuring silica, sericite, chlorite, and pyrite, and include mafic schists, volcaniclastics, volcanic rocks, and non-carbonaceous interflow sediments. Notably, earlier-stage volcanics and volcaniclastics have been subjected to deformation, flooding, and hydrothermal alteration. Deep-seated mantle-derived lamprophyres are also present, indicating ongoing mantle interactions and potential pathways for mineralising fluids descending from deeper sources. Within the footwall, a localised dolerite intrusion hosts the Iris, Ra, Wadget, and Tefnut lodes different mineralised zones identified based on their spatial location. The medium-coarse grained dolerite often displays alterations such as silica, chlorite, K-feldspar, and pyrite, with gold thought to be deposited within quartz veins at the margins of these intrusive bodies.
The structural regime within the Apollo Hill system plays a critical role in controlling mineralisation patterns and fluid conduits. The dominant shear zone strikes approximately 010°, dips 40° to 60° northeast, and represents an area of extreme strain where rocks have been deformed beyond recognition of their original lithology. This zone acts as a major regional fluid pathway and control point for gold deposition, with evidence of conjugate shears, faults, and cross-cutting dilatational zones observed through aeromagnetic and gravity surveys. Four principal structural orientations have been identified: the predominant N-S structures, which are believed to be the controlling conduits for mineralisation and exhibit sinistral (left-lateral) shear movement; the NNE-SSW, NE-SW, and E-W trending faults, which are generally shallow-dipping thrust faults that juxtapose different lithologies. These secondary structures, although not primary mineralisation hosts, are crucial in facilitating fluid flow and creating rheological and redox boundaries that localise mineral deposits, especially at their intersections.
The mineralisation at Apollo Hill reflects a multi-stage history of gold deposition. Multiple generations of quartz veins have been recognized, with some sets forming discontinuous sheeted or stockwork veins dipping at approximately 53° towards the northeast. Vein thickness varies from a few millimeters to centimeters, with higher vein density correlating with increased gold grades. These veins often display deformation, including boudinage, folding, extensional strain and shearing, indicating a dynamic deformation history.
Dimensions
Apollo Hill mineralisation has an approximate north-west to south-east strike length of 1.4-5km, variable width of up to 400m (including the similar Hanging Wall Zone), and down dip extent of more than 600m.
Ra mineralisation is fragmented along a north-west to south-east strike length of 2.1km, variable width of up to 25m, and down dip extent of up to 300m.
Tefnut mineralisation is variable with some evidence of an en echelon arrangement and appears to have a north-west to south-east strike length of 500m, variable widths of up to 20 m, and down dip extent of up to 250m.
Mineralisation extends to near surface, truncated in some area by a thin layer of barren transported cover sediments. The mineralisation is not closed-off by the resource definition drilling either along strike, across strike to the north-east or down-dip, although a decreasing grade trend along strike at the current limits is observed.